For coating materials for various structures, fluorine coating materials having excellent water resistance and weather resistance have been used up until now. Fluorine coating materials, however, have a disadvantage that they have insufficient adhesion to a substrate and insufficient water resistance.
Patent Literature 1 teaches a water-based fluoropolymer dispersion obtained by emulsion-polymerizing a monomer mixture containing an acrylic acid alkyl ester and/or a methacrylic acid alkyl ester, and an ethylenically unsaturated monomer copolymerizable with these esters, in an aqueous medium. Patent Literature 1 also teaches that the adhesion can be significantly improved when the ethylenically unsaturated monomer is a monomer containing a cyclohexyl group.
Patent Literature 2 teaches an aqueous coating composition obtained by a production method including (1) a step for preparing an aqueous dispersion of fluorine-containing polymer particles by polymerization of monomers comprising at least one fluoroolefin in an aqueous dispersion in the presence of a surfactant, and (2) a step for seed-polymerizing an ethylenically unsaturated monomer with fluorine-containing polymer particles in the aqueous dispersion of fluorine-containing polymer particles. Also, Patent Literature 2 teaches that use of a compound represented by CH2—CHCH2—O—R (wherein R is a hydrocarbon group which may have an oxygen atom, a nitrogen atom and/or a polar group) as the surfactant used in the step (1) improves the adhesion to a substrate, foamability, and gloss.
As described above, technologies for improving the adhesion have been developed, but further improvement in the adhesion and water resistance is desired.